Participate in employer match 401k or not?

[Jay Helms]

My employer provides a match (up to 3%) when I contribute to their sponsored 401k. I don't like contributing because I know the return is not as good on the 401k as it is on my B&H properties. I'm contemplating discontinuing my contribution to invest those monies in RE, however, I hate the idea of losing "free money" (my employers match). What are some equations to use to evaluate my scenario and/or what do you do?